1 10 4 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/7eda87156991f7c8b27a0e8510940358.jpg 2635d861ca5b4c2cbbd828726c95bfd4 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/dcc7eadcc1e8adacfb3ca0062cf15b41.jpg 35dd6efe13e1fca981d0837a56294e0b https://wserv3.esc.cam.ac.uk/p1acollections/files/original/4df0492facb5854e9375d2f627f192fe.jpg ffc9075681e5de8a163ba2009ad46bb1 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/52688639ee0b849fb604e43c822c434b.jpg 27a1d7561ed102f3dc1de4996962dd8d Physical Object An inanimate, three-dimensional object or substance. Note that digital representations of, or surrogates for, these objects should use Moving Image, Still Image, Text or one of the other types. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource <h2>Alkali feldspar</h2> Description An account of the resource <div class="element"> <div class="element"> <h3>Formula</h3> <div class="element-text"> <p>(K,Na)[AlSi₃O₈]</p> </div> </div> <div class="element"> <h3>Structure</h3> <div class="element-text"> <p>Framework silicate</p> </div> </div> <div class="element"> <h3>Crystal System</h3> <div class="element-text"> <p><em>Crystal system:</em><span> </span>monoclinic (-) or triclinic (+) (-)</p> </div> </div> <div class="element"> <h3>Physical Properties</h3> <div class="element-text"> <p class="NoSpacing"><em><span>Colour in hand specimen:</span></em><span> white or pink</span><span> </span><br class="NoSpacing" /><em><span>Cleavage:</span></em><span> two at 90°</span><span> </span><br class="NoSpacing" /><em><span>Hardness:</span></em><span> 6-6.5</span></p> </div> </div> <div class="element"> <h3>Optical Properties</h3> <div class="element-text"> <p class="NoSpacing"><em>Colour in plane polarised light:</em><span> </span>colourless<span> </span><br class="NoSpacing" /><em>Pleochroism:</em><span> </span>none<span> </span><br class="NoSpacing" /><em>Relief:</em><span> </span>low<span> </span><br class="NoSpacing" /><em>Birefringence:</em><span> </span>~0.008; 1^st<span> </span>order greys<span> </span><br class="NoSpacing" /><em>Extinction:</em><span> </span>inclined<span> </span><br class="NoSpacing" /><em>Twinning: </em>usually simple or lamellar;<span> </span><br />              Microcline (KAlSi₃O₈) displays characteristic cross-hatched twinning</p> </div> </div> <div class="element"> <h3>Mineral Specimens</h3> <div class="element-text"> <p class="NoSpacing"><strong><span>M400 </span></strong><strong><span>Alkali feldspar, microcline</span></strong><span> </span><br class="NoSpacing" />A single crystal of pale orange-pink alkali feldspar.<span> </span><br class="NoSpacing" />Pearly lustre.</p> <p class="NoSpacing"><strong><span>M401 </span></strong><strong><span>Alkali feldspar, orthoclase</span></strong><span> </span><br class="NoSpacing" /><strong>Norway</strong><strong></strong><span> </span><br class="NoSpacing" />A fragment of opaque, pale grey alkali feldspar.<span> </span><br class="NoSpacing" />Two sets of good cleavage at right angles, with a pearly lustre on the cleavage faces.</p> <p class="NoSpacing"><strong><span>M402 </span></strong><strong><span>Alkali feldspar, orthoclase</span></strong><span> </span><br class="NoSpacing" /><strong>Shap, Westmorland</strong><span> </span><br class="NoSpacing" />Porphyritic granite.<span> </span><br class="NoSpacing" />Large phenocrysts of pink feldspar, two sets of cleavage at 90°, simple twinning.<span> </span><br class="NoSpacing" />Also white plagioclase feldspar, quartz and biotite<strong>.</strong></p> </div> </div> <div class="element"> <h3>Rock Specimens</h3> <div class="element-text"> <p><a href="/p1acollections/exhibits/show/igneous-rocks/l100">L100 Alkali granite</a><span> </span><br /><a href="/p1acollections/exhibits/show/igneous-rocks/l101">L101 Granite</a><span> </span><br /><a href="/p1acollections/exhibits/show/igneous-rocks/l102">L102 Hornblende biotite granite</a><span> </span><br /><a href="/p1acollections/exhibits/show/igneous-rocks/l110">L110 Rhyolite, porphyritic (quartz porphyry)</a></p> </div> </div> <div class="element"> <h3>Mineral Name</h3> <div class="element-text">alkali feldspar</div> </div> </div> felsic granite rhyolite https://wserv3.esc.cam.ac.uk/p1acollections/files/original/12b5c18a74215d375e002f21037f4df9.jpg 113d76f170e53159aa1248482d0c7b82 Physical Object An inanimate, three-dimensional object or substance. Note that digital representations of, or surrogates for, these objects should use Moving Image, Still Image, Text or one of the other types. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource <h2>Tourmaline</h2> Subject The topic of the resource <span>Tourmaline is the only common mineral of which boron is an essential constituent. Its presence in a rock, therefore, indicates that the rock contains significant boron. </span> Description An account of the resource <div class="element"> <h3>Formula</h3> <div class="element-text">(Na,Ca)(Mg,Fe,Mn,Li,Al)₃(Al,Mg,Fe³⁺)₆[Si₆O₁₈](BO₃)₃(O,OH)₃(OH,F)</div> </div> <div class="element"> <h3>Structure</h3> <div class="element-text"> <p>Ring silicate</p> </div> </div> <div class="element"> <h3>Crystal System</h3> <div class="element-text"> <p><em>Crystal system:</em><span> </span>trigonal (-)</p> </div> </div> <div class="element"> <h3>Physical Properties</h3> <div class="element-text"> <p><em>Colour in hand specimen:</em><span> </span>black<br /><em>Hardness:</em><span> </span>7</p> </div> </div> <div class="element"> <h3>Optical Properties</h3> <div class="element-text"> <p><em>Colour in plane polarised light:</em><span> </span>typically brown-green or green<br /><em>Pleochroism:</em><span> </span>strongly pleochroic in many colours<br /><em>Relief:</em><span> </span>moderate<br /><em>Birefringence:</em><span> </span>typically 2nd order</p> </div> </div> <div class="element"> <h3>Rock Specimens</h3> <div class="element-text"> <p><a href="/p1acollections/exhibits/show/metamorphic-rocks/l504">L504 Garnet schist</a></p> </div> </div> <div class="element"> <h3>Mineral Name</h3> <div class="element-text">tourmaline</div> </div> granite metapelite pegmatite https://wserv3.esc.cam.ac.uk/p1acollections/files/original/5e37a66fc246f7e8a088a4e4c0d011bd.jpg 541861a9fa9a4ae459f66f0e9c425bb3 Physical Object An inanimate, three-dimensional object or substance. Note that digital representations of, or surrogates for, these objects should use Moving Image, Still Image, Text or one of the other types. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource <h2>Zircon</h2> Description An account of the resource <div class="element-set"> <div class="element"> <div class="element-text"> <h3>Formula</h3> </div> </div> </div> <div class="element-set"> <div class="element"> <div class="element-text">Zr[SiO₄]</div> </div> <div class="element"> <h3>Structure</h3> <div class="element-text"> <p>Orthosilicate</p> </div> </div> <div class="element"> <h3>Crystal System</h3> <div class="element-text"> <p><em>Crystal system:</em><span> </span>tetragonal (+)</p> </div> </div> <div class="element"> <h3>Physical Properties</h3> <div class="element-text"> <p><em>Colour in hand specimen:</em><span> </span>reddish brown, yellow, grey, green or colourless<br /><em>Hardness:</em><span> </span>7.5</p> </div> </div> <div class="element"> <h3>Optical Properties</h3> <div class="element-text"> <p><em>Colour in plane polarised light:</em> colourless to pale brown<span> </span><br /><em>Pleochroism:</em> very weak<br /><em>Relief:</em> high<br /><em>Birefringence:</em> 0.042-0.065; 3rd order green to 4th order green<br /><em>Extinction:</em> straight<br /><em>Twinning:</em> rare</p> </div> </div> <div class="element"> <h3>Rock Specimens</h3> <div class="element-text"> <p><a href="/p1acollections/exhibits/show/igneous-rocks/l100">L100 Alkali granite</a></p> </div> </div> <div class="element"> <h3>Mineral Name</h3> <div class="element-text">zircon</div> </div> </div> Subject The topic of the resource Zircon is a common accessory mineral of many igneous rocks. Pleochroic haloes are formed by damage to the crystal lattice of enclosing minerals by the radioactive decay of elements such as Th and U in zircon. These may be particularly noticeable in biotite grains in old granitic rocks. granite radiation thorium uranium https://wserv3.esc.cam.ac.uk/p1acollections/files/original/e3160631658548f9f2dc6e1becea70da.jpg d95ec5a176a934d2c3e57276e230693c https://wserv3.esc.cam.ac.uk/p1acollections/files/original/e2173d02d96267ba32160e6fdf7413e7.jpg 6064d39c4c259244a0f9ee941313b06b https://wserv3.esc.cam.ac.uk/p1acollections/files/original/01845924716bedfe0fd182d669f227cd.jpg 29966d5660a6a3fe8f268bf574236f17 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/16d925108b74372b95b4fdde50676900.jpg 5258ac41a282f9310c3fe1c4115cc800 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/f8b28219498294d826754ab3542fb00f.jpg c99a49a3bc0d2fc2234806df01cd66c1 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/ac59d17b2a65340795a83853876e0422.jpg 27acfdf84cb9a638c01a6ee7daebba0e Physical Object An inanimate, three-dimensional object or substance. Note that digital representations of, or surrogates for, these objects should use Moving Image, Still Image, Text or one of the other types. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource <h2><strong>L102<br /></strong></h2> <h2>Hornblende biotite granite</h2> Subject The topic of the resource <h3>Age</h3> <div class="element-text"> <p>Caledonian, Devonian</p> <h3>Location</h3> <div class="element-text"> <p>Glencoe</p> </div> </div> Description An account of the resource <div class="element-set"> <div class="element"> <div class="element-text"> <div class="element-set"> <div class="element"> <div class="element-text"> <h3><span style="font-size:14px;">Hand Specimen</span></h3> </div> </div> </div> <div class="element-set"> <div class="element"> <div class="element-text"> <p>Medium to coarse-grained rock with a<span> </span><a href="/p1acollections/items/show/203">granular</a><span> </span>texture.<span> </span><br />White feldspar<span> </span><a href="/p1acollections/items/show/215">laths</a><span> </span>2-4 mm long are clearly visible.<span> </span><br />Other phases: pink feldspar, black biotite mica, black hornblende amphibole and pale grey quartz. These grains are more<span> </span><a href="/p1acollections/items/show/188">equant</a>, typically 1-2 mm across.<span> </span><br />Biotite may be distinguished from hornblende by its flaky<span> </span><a href="/p1acollections/items/show/206">habit</a><span> </span>and one good<span> </span><a href="/p1acollections/items/show/180">cleavage</a>. It is shinier than hornblende.</p> </div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text"> <p>Plagioclase feldspar<span> </span><br />- The larger laths (2-4 mm long) are strongly<span> </span><a href="/p1acollections/items/show/267">zoned</a>. The cores of these laths, which display clear<span> </span><a href="/p1acollections/items/show/169">lamellar twinning</a>, have been<span> </span><a href="/p1acollections/items/show/232">overgrown</a><span> </span>by rims of more feldspar. Some<span> </span><a href="/p1acollections/items/show/170">alteration</a><span> </span>to white mica.</p> <p>Biotite mica<span> </span><br />- Grains typically 1 mm across. Strongly pleochroic in reddish brown and pale straw. Often associated with small grains of an opaque accessory mineral, probably magnetite.</p> Quartz<span> </span><br />- Grains are 1-2 mm across,<span> </span><a href="/p1acollections/items/show/173">anhedral</a>, and display<span> </span><a href="/p1acollections/items/show/263">undulose extinction</a>. <p>Alkali feldspar<span> </span><br />- Anhedral grains up to 5mm long. Some alteration to white mica. Some grains display a<span> </span><a href="/p1acollections/items/show/228">microperthite texture</a>.</p> <p>Hornblende amphibole<span> </span><br />- Pale green, anhedral. Grains appear to have been “eaten away”, reducing their<span> </span><a href="/p1acollections/items/show/246">prismatic</a><span> </span>form (diamond) to a ragged anhedral<span> </span><a href="/p1acollections/items/show/206">form</a>. Amphiboles have two cleavage planes which intersect at 56°.</p> </div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text">This coarse-grained rock must have cooled slowly as part of an intrusion.<br /><br />Its granitic composition (essential quartz and feldspar) indicates that it was produced in a continental setting.<br /><br />Strongly zoned plagioclase crystals and “eaten away” appearance of the hornblende could be due to a change in the composition of the liquid from which the phases crystallised; perhaps due to magma mixing or degassing of volatiles from the magma.<span> </span><br /><br />Presence of hornblende and biotite indicate that this is a wet granite, probably from a subduction zone.<br /><br />Hydrothermal alteration of feldspars to white mica.</div> </div> <div class="element"> <h3>Advanced Notes</h3> <div class="element-text"> <p>This rock is classified as an<span> </span><span>adamellite</span><span> </span>because it contains roughly equal proportions of alkali feldspar and plagioclase feldspar, with additional quartz and biotite.</p> </div> </div> <div class="element"> <h3>Rock Name</h3> <div class="element-text"> <p>hornblende biotite granite<br />adamellite</p> </div> </div> </div> </div> </div> </div> arc biotite coarse granite hornblende subduction